AirSpaceMag.com

How Things Work: Phased-Array Radar

It takes a big eye to see a missile coming

The SBX, shown here on a cargo vessel in Texas, practiced two days of "weather avoidance" when Hurricane Emily arrived in the Gulf of Mexico during 2005 testing. The range of the array inside the dome is limited only by Earth's curvature.
(Boeing)

Since the main beam can be pointed almost instanteously, it can jump from object to object as they come into range.

Phased-array radars are not without disadvantages. Most are functional through a cone of just 120 degrees, because the width of the main beam diminishes the farther it gets from broadside. As an example, think of how narrow your wide-screen television looks when you’re in an adjacent room.

For this reason, at least four radars are needed to cover a hemisphere. To compensate for the narrow field of view, the SBX’s main array rotates and tilts; it’s one of the few phased arrays to do that.

Although the initial cost is 100,000 times more expensive than a conventional radar with the same beam width, a phased-array device may be cheaper long-term because the system will still function as needed even if many of its smallest components fail.